Crows & Birdbaths part 2

I'm still watching the crows at the birdbath, and I've come to the conclusion that most of what they're bringing is not, after all, roadkill (There was one stretchy thing I'm glad I didn't get a good look at). Mostly, it seems to be stuff from one of the nearby restaurants--chicken bones that they strip the meat from and sometimes crack, or bread--twice it was big hunks of it that the crow in question left floating in the bath and then returned to intermittently throughout the day. In between crow visits, the other birds came down to munch.

Once it was a large, live grasshopper that the crow very efficiently dismembered at the edge of the bath. I don't know if that was a case of "handy edge" or "chitin is easier to swallow wet."

They (or it--I'm not sure how many crows are involved. We have a group of 2-3 that hangs out regularly, but whether they are the same 2 or 3, I don't know. Anyone know who can legally tag crows for the benefit of casual, front-yard observers?) haven't used the bath for food softening as much lately. I thought maybe the restaurant had made their bins crow-inaccessible, but now I think there may be another explanation. The crow in the picture there would very much like to settle down for a drink or a bath but is instead cawing in frustration (an attempt to call other crows? Anger?) because he's being persistently dive-bombed by mockingbirds. We have lots of those around, it's nesting season, and they do not like crows at all. So, possibly the bath will again be filled with debris in the winter and this is only a momentary reprieve, granted by the busy mockingbirds (who might as well do something other than sing at midnight).